In 1990 U.S. railroads were hauling all commodities for an average freight rate of 2.7 cents per revenue ton mile compared to 8 cents per revenue ton mile for regulated gravel trucks. In order for railroads to take maximum advantage of their low costs, it is necessary for trains to be able to deliver directly to construction sites, rather than to unload into stock piles or into trucks for the final transportation to the user. This type of delivery is made possible in many cases because many highways were built adjacent to railroads. Also, many industrial plants were served by railroad tracks within the plants.
The present inventor is the owner of U.S. Pat. Nos. 4,925,356, issued May 15, 1990 for a "Self-Unloading Train for Bulk Commodities" and in U.S. Pat. No. 4,958,977, issued on Sep. 25, 1990 for a "System for the Transport of Bulk Commodities". The subjects of U.S. Pat. Nos. 4,925,356 and 4,958,977 have been commercially produced and sold by Conveying & Mining Equipment, Inc. of Houston, Tex. The product manufactured by this company under U.S. Pat. No. 4,925,356 is commonly known by the commercial trademark "DUMP TRAIN". The DUMP TRAIN is a unit train consisting of a plurality of hopper cars and a multi-purpose trailer car. The hopper cars have hoppers which have a bottom discharge opening and a controllable gate. An endless belt conveyor traverses the length of the train including a portion of the trailer car. The hopper discharge gates can be emptied sequentially onto the train conveyor so as to unload the entire train. This allows the DUMP TRAIN to deliver aggregate material to areas served by railroad tracks. Prior to the development of the DUMP TRAIN, it was necessary for such hopper cars to deliver their loads to unloading facilities. From the unloading facilities, it was necessary for trucks, or other modes of transportation, to haul the aggregate to the desired work site. The development of the DUMP TRAIN allowed the railroads to serve areas that were previously inaccessible by rail or by truck.
U.S. Pat. No. 4,958,977 describes a product that is known in the trade by the trademark "SLOT MACHINE". The SLOT MACHINE is a material transport system having a material container which extends along a flat floor throughout the length of the train. A pair of side walls extend upwardly on each side of the flat floor. An unloader, in the form of a tractor/bucket, is placed into this flat roadway within the train so as to carry out the mechanical loading and/or unloading of the train. The SLOT MACHINE was developed to further utilize the economics of rail transportation for the delivery of material to desired locations.
The ability of the SLOT MACHINE and the DUMP TRAIN to serve work sites is somewhat limited by the location of the railroad tracks. Ultimately, it would be desirable to be able to install rail lines that extend from the main line to the work site. It is also important to be able to connect the main line to existing, generally unused, track that extends into areas of need.
A limitation on the ability to move the SLOT MACHINE, the DUMP TRAIN, and other forms of rail transportation, to remote work sites is the cost, trouble, and difficulty of installing switching systems off the main line. Typically, switching systems are extremely expensive, require railroad approval, and must be maintained constantly. Typical railroad switching systems are unsuitable for the occasional use that would be required of them for the delivery of aggregate materials along branch lines to work sites. Each switching system must be adapted to the particular needs along the given area of rail track. There is no current switching system that is economically and practically possible when the branch line is only used occasionally.
In some cases, it is practical for unit trains like the DUMP TRAIN or the SLOT MACHINE to make deliveries from railroad main lines. However, this is potentially disruptive of the business of the railroads. The utilization of the DUMP TRAIN or the SLOT MACHINE on the main lines of the railroad should be avoided if at all possible. In most cases, it is desirable to have a switch or "turnout" to allow trains to get off the main lines and onto temporary tracks, or branch lines, for delivery purposes.
Switches are a major source of concern for trunkline railroads. They require far more maintenance than ordinary track. Unless such switches are under close control by railroad personnel, they can easily be the cause of derailments and train wrecks. In particular, centralized traffic control is sensitive to switches. The position of every switch on the main line must be constantly monitored by the dispatcher and his computer. In many cases, the switch can be operated by a dispatcher a thousand miles away. However, it is not sufficient to give the order to turn a switch. It is also essential to have the feedback to know that the switch is safely aligned in the desired position. The long communication lines for control and feedback can be a large part of the capital costs of a railroad switch.
For these reasons, railroads are reluctant to install new switches in their territory. They must be assured of a large volume of traffic to economically justify the direct costs, added risks, and supervision.
Nearly all switches that are installed on the main line of the railroad are designed for fairly high speed trains, some as high as ninety miles per hour. In contrast, the delivery of construction materials, such as by the DUMP TRAIN or by the SLOT MACHINE, is done at very low speeds. A switch capable of handling a train at five miles per hour, or less, is adequate for the purpose of the delivery of construction materials.
Various United States patents have been issued in the past which attempt to address the problems of railroad switches and which describe various frog systems. U.S. Pat. No. 154,439, issued on Aug. 25, 1874, to B. Bacon was an early development in the technology of railroad switches. This early development in switches formed a railway switch by raising the switch-wheels the width of the wheel flanges higher than the main rails, so as to dispense with frogs and nearly all of the guide rails of ordinary switches.
U.S. Pat. No. 712,802, issued on Nov. 4, 1902, describes a railroad frog which utilizes an elevating lateral rail (or shoe) provided with a longitudinal groove inclined downwardly and convergently joined to a main-track rail. A rail is arranged on the opposite side of the main-track rail and is adapted to receive the tread of the car wheel which is elevated by the lateral track. This enables the wheel to clear the main track rail.
U.S. Pat. No. 787,711, issued on Apr. 18, 1905, shows an emergency switch and frog. In this system, the main line has a hinged point of which one part of the point passes upon and over the main rail and another part of the point enters the groove of the main rail combined with a clamp and a wedge for securing the main rail.
U.S. Pat. No. 820,406, issued on May 15, 1906, shows a railroad frog system which consists of a rail-section swinging from one end between the terminals of two adjacent track-rails to fill the intervening gap and to produce a continuous line of rails. The rail section has a laterally extending base of greater width than the height of the rail.
U.S. Pat. No. 891,411, issued on Jun. 23, 1908, describes a switch operating apparatus, in the form of a frog, which is remotely operated by the moving car.
It is an object of the present invention to provide a frog switching system that is simple to manufacture, easy to install, and relatively inexpensive.
It is another object of the present invention to provide a railroad frog system that enhances the ability of the main railroad line to serve branch lines.
It is a further object of the present invention to provide a railroad frog system that can be manually installed and operated.
It is still a further object of the present invention to provide a railway frog system that does not interfere with the operation of rail traffic from the main line.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.